The invention relates to an apparatus for the sterilization of containers and, in particular, an inner wall of containers by means of accelerated charge carriers with a charge carrier source for producing the charge carriers, with an acceleration device by which charge carriers are capable of being accelerated in the direction of a charge carrier emission window, the charge carrier emission window being arranged on a treatment device which is capable of being introduced through an opening into the container along an insertion direction, in order to act upon an inner wall of the container with the charge carriers issuing from the charge carrier emission window, the treatment device having a medium line with a medium emission opening, the medium emission opening of which is preferably capable of being introduced through the opening into the container.
The invention further relates to a plant for the treatment of containers, which has at least one apparatus for sterilizing containers, as well as to a method of sterilizing containers and, in particular, an inner wall of containers by means of accelerated charge carriers, the charge carriers being generated in a charge carrier source and being accelerated by an acceleration device in the direction of a charge carrier emission window, the charge carrier emission window being arranged on a treatment device which is introduced through an opening into the container along an insertion direction, in order to act upon an inner wall of the container with the charge carriers issuing from the charge carrier emission window, the treatment device having a medium line with a medium emission opening, the medium emission opening of which is capable of being introduced through the opening into the container.
As well as the actual filling procedure, the sterilization of a container to be filled is the central process step in an aseptic filling plant. The possible forms of sterilization vary with respect to the disinfectants and the performance of the process. What they all have in common, however, is that the destroying action is carried out on the basis of chemical processes. In this way, it is known for example for the inner wall of containers to be sterilized with steam or hydrogen peroxide. Methods of this type, however, are subject to drawbacks since the treatment with hydrogen peroxide for example can result in a softening of the material. Recent developments differ from this and use ionizing radiation in order to achieve a reduction in germs. In most applications this radiation comprises accelerated electrons which are produced in a suitable plant and are introduced into the container to be sterilized. This results in a reduction or complete avoidance of the use of chemical substances and inter alia a reduction in the costs of acquisition and disposal.
The terms “container”, “receptacle” and “plastics material container” are used synonymously below for the sake of simplification. In this case these terms also include preliminary products of containers of this type. In particular, these terms relate to bottles, preferably drinks bottles, but also to pre-forms (plastics material pre-forms for example for bottles for example).
Suitable systems for sterilization known from the prior art comprise an electron production apparatus and a bundling device. Charge carriers produced outside the container to be sterilized are directed by various elements, for example mechanical or electronic elements, into the container to be sterilized. In the latter a cloud of electrons is formed which deactivates any undesired micro-organisms by interaction with the latter.
In this way, DE 198 82 252 T1 describes a technique for the internal sterilization of a container by means of electrons. In this case an electron beam source is likewise provided which directs the radiation into the interior of the container from the outside.
Methods are also known, such as for example from the publication WO 97/07024 A, in which at least parts of the electron source can be introduced into the interior of the container. A method of cleaning and sterilizing packages of products by means of a combination of an electron beam and a gas jet is described. The apparatus disclosed in WO 97/07024 A comprises an electron gun which is capable of being introduced in part into the interior of a container and which introduces accelerated electrons into the interior of a container. A flow—introduced parallel thereto—of a gas interacting with the electron beam is used either for deflecting the electron beam in the direction of the gas flow or, on the other hand, as an auxiliary agent for sterilization by ionization of the gas.
In many cases, however, it is also desirable for the geometry of the electron cloud to be changed, and in particular for the extension thereof to be reduced. An advantage of a process with a controlled reduction of the electron cloud consists in the possibility of the radiator power and thus also the dimension of the resulting cloud being adapted to containers which are reduced for example, such as for example container pre-forms, without changing the radiator setting, for example the acceleration voltage. Excessively accelerated electrons could penetrate too deeply into the material of the pre-form, without being able to interact to an adequate degree with the surface and contamination present on the latter and thus being able to sterilize the surface. In addition, excessively accelerated charge carriers could possibly—depending upon the material of the container used—also damage the material of the container.
It would be particularly advantageous if the extension of the electron cloud could be reduced into one region in which the radiation which is issuing from the treatment device and which can include both the charge carrier beam and also interfering radiation, for example x-ray radiation, can be substantially screened off from the environment and, in this way, in the event of a removal of the treatment device from the container to be sterilized, an unnecessary exposure of the environment to radiation can be avoided. This could be advantageous for example in the case of a change of the containers to be sterilized, in which the treatment device and thus also the electron cloud discharged are outside a container for a brief time.
The object of the invention is therefore to provide an apparatus for the sterilization of containers, which will make it possible, without switching off or changing the acceleration voltage, to change, and in particular to reduce, the dimension of an electron cloud radiated by a treatment device.
Since, in particular, high clock-time rates and throughput figures are achieved in the plants used for the production and filling of containers, it is in addition an object of the invention to provide a suitable plant for the treatment of containers, which includes an apparatus of this type for the sterilization of containers.
In addition, it is an object of the invention to provide a method of sterilizing containers, which will make it possible, without switching off or changing the acceleration voltage, to change and, in particular, to reduce the dimension of an electron cloud radiated by a treatment device.